Drilling fluids or mud are commonly used in the oil and gas drilling industry. Mud is used to maintain borehole pressure equilibrium and to remove bit cuttings. Mud is typically a highly lubricating slurry of clays and fluid. One such mud, containing potassium chloride, is referred to as KCl mud. This process has been developed in connection with treatment of KCl mud, although it is not limited to it. After drilling a well, significant quantities of spent mud remain. Typically, a used KCl mud may contain 40,000 ppm of salt in an aqueous bentonite clay slurry.
In the past, the used mud has been mixed with soils or otherwise spread on fields for disposal. The increase in regulations for disposal of noxious materials and the level of salts in this particular type of used drilling mud has made disposal difficult and expensive.
Prior methods of disposal include diluting the mud with water, to reduce the fractional KCl levels to acceptable disposal limits (ie. 5,000 ppm KCl), and then spraying it on fields. This has been a very expensive process. Additionally, the highly diluted mud is also mobile and amenable to leaching and transport of salts by rain water. This leads to accumulation and high concentration of salts in low areas of the field, thus ultimately failing the disposal criteria.